The present invention is directed to a runner and to a suspended ceiling system having many runners and cross-runners for supporting ceiling panels. Each of the runners has a substantially inverted T configuration with an upper bead connected by webs to outwardly directed flange elements which have a first flange portion connected by an offset portion to a second flange portion so as to form a downwardly opening groove. The exposed surfaces of the flange elements and the groove are covered by a cap member having a channel so that changes in the color of the flanges can be obtained by changing the cap. In addition, the system utilizing the runners has the connective joints which provide a fire-rated system because it allows for limited expansion of the cross-members when subjected to elevated temperatures.
Suspended ceiling support systems or structures, which utilize a plurality of main runners or members and cross-members or runners are shown in a number of U.S. patents. One such system is described in U.S. Pat. No. 4,525,973 and this system has an inverted T-shaped structure whose outwardly extending flat flanges are covered by a cap member which can be viewed by the occupants of a room utilizing the ceiling structure. The standard total width for the pair of flanges is approximately one inch. Instead of having a flat flange such as disclosed in the above-mentioned patent, it has been proposed for aesthetic reasons to provide the runners with a narrower flange and a narrower flange with a longitudinally extending recess. Different ways of obtaining these types of structure are disclosed in U.S. Pat. Nos. 4,034,531; 4,470,239; 4,489,529 and 4,505,083.
In the ceiling system of U.S. Pat. No. 4,034,531, a T member has a box-like member, which is provided with a longitudinally extending groove, secured thereto. The structure also requires panels which have rabbet edges so that a recess is formed at the edges of the panels for receiving this box member when the panels are supported by the runners.
In the arrangement of the structure of U.S. Pat. No. 4,470,239, the runner is formed from a single piece of metal which has a bead with two web portions extending down in an inverted V shape and terminating in outwardly extending flanges. The webs are resilient to each other so as to act to center the panels to provide proper support even though the flanges are of a substantially narrower configuration than the flange of a standard runner.
U.S. Pat. No. 4,489,924 discloses a runner with a T shape or bar configuration that has a cap member. The flange is approximately 5/16 of an inch wide and webs are held together by lances or stitches.
In U.S. Pat. No. 4,505,083, each of the runners has a bead with two webs extending downwardly and being bent to form flange elements having different configurations and a cap is applied to these flange elements so that the exposed portion observed by a person in the room having the ceiling structure will see the cap member. As illustrated, the construction can provide a shallow V-shaped groove, a rectangular groove, a groove having a trapezoidal configuration and other possible groove shapes. In addition, to provide the connections between the cross-runner and main runners, notches and tapered ends are formed. While this provides an aesthetic structure, it does have a disadvantage of greatly reducing the rigidity of the main runner particularly during installation because of the notches in the flange elements.
In addition to preparing a runner which has a new aesthetic look, it is also desirable to provide a ceiling system which is fire-rated and can allow for expansion of the cross-runners when subjected to an elevated temperature without buckling of the runners to drop the panels.